No matter what your UV-Vis NIR spectrometer needs are, Excedr can assist your lab. Contact us today and learn how, regardless of the make, model, or configuration our leasing program can save you time and money on your NIRS device.

Light can be defined as a type of energy. Light particles, or photons emit electromagnetic radiation that has a specific wavelength and frequency. These electromagnetic waves have different properties depending on their wavelength and frequency. For example, electromagnetic waves with wavelengths between 450 nanometers (nm) appear blue. The electromagnetic spectrum organizes all classes of light and their corresponding frequencies and wavelengths. Visible, ultraviolet, and infrared radiation are three such groups.

Ultraviolet or UV is typified as having wavelengths of 10 nanometers (nm) to 400 nm. The most well-known UV radiation comes from the sun, and its effect on our skin is why people need to wear sunscreen. UV radiation is subdivided into UV-A, UV-B, and UV-C subcategories depending on their wavelength and the amount of energy they possess. UV radiation lies along the violet portion of the electromagnetic spectrum and has shorter wavelengths than visible light which lies between 400 nm to 700 nm.

Infrared radiation also called IR, is characterized by having a longer wavelength than the visible light radiation wavelength. This means that IR is not visible to humans. Within the IR spectrum, there are other subdivisions including near-infrared. Near-infrared or NIR have wavelengths from .75 to 1.4 micrometers and a frequency of 214 to 400 terahertz. They have a wide range of applications including in night vision devices as well as the spectroscopic study of materials.

Ultraviolet-Visible (UV-Vis) spectroscopy is a form of spectroscopy that uses the UV and visible portion of the electromagnetic spectrum to look at properties of a substance. Observing how matter interacts with UV and or vis light whether it is through absorption or reflection. Interactions in this portion of the spectrum result in organic molecules undergoing molecular electronic transition. This is to say that these interactions result in electrons in the molecules becoming energized or excited. For visible light specifically, the reflection of light results in humans ability to see color. An important law that is used in the application of UV/Vis spectroscopy is the Beer-Lambert law which states that the higher the concentration of a molecule, the more UV/Vis radiation it will absorb. The structural component responsible for this absorption is called a chromophore. Due to the linear relationship of this law, UV-Vis spectroscopy is an important tool in chemistry for the quantitative determination of analytes in a compound.

Near-infrared spectroscopy or NIRS, is a non-destructive analytical technique that measures how samples absorb NIR light to observe their properties. While UV-Vis observes energy transitions, NIRS looks at vibrational transition. NIRS shoots a sample with a broad-spectrum of NIR light and analyzes what wavelengths are absorbed, reflected, or scattered by the material. This data can then be used to determine properties about the bonds of the molecules that are in the object of interest. Bond vibrations between hydrogen and other elements such as oxygen (OH), carbon (CH), and nitrogen (NH) are seen as NIR absorbance bands. The spectral bands that NIRS gathers are wide which can make their interpretation more complex than other spectroscopy methods, however, their ability to penetrate deep into samples makes them a useful tool.

UV-Vis and NIRS Instrumentation & Costs

UV-Vis and NIRs setups differ in many important ways, but their basic setups consist of a light source, a filter, and a detector. They may also have a dispersion unit that makes analyses at different wavelengths possible. The filters that are used are employed to limit or select specific wavelengths that you wish to observe. Depending on what properties are being looked for in the sample, the set specific instrumentation that is used varies.

Light SourcesFor both spectroscopy techniques, specific light sources must be used to reproduce UV, Vis, and or NIR light. UV-Vis radiation sources may be tungsten or mercury lamps. UV specific light sources include deuterium, xenon discharge, and hydrogen lamps while Vis radiation sources also include carbonone lamps. The light sources shoot light through a clear tube-like container that has specific outer and inner dimensions holding the sample. These transparent cuvettes are often plastic, glass, or quartz. For NIR radiation analysis the most commonly used optical component is an incandescent or quartz halogen light bulb. Light-emitting diodes are also used, however, their spectral coverage is narrow, spanning only from 50-100 nanometers. For analysis requiring a narrower range or more precise measurements, lasers and frequency combs are used.

DetectorsFor UV/Vis spectroscopy there are three common types of detectors used:

Barrier layer cell or photovoltaic cells: They consist of two thin metallic layers, often copper or iron, where one acts as a base plate and the other an electrode. A semiconductor, such as selenium, is deposited on them and, finally, a thin layer of either silver or gold covers them. When radiation hits the semiconductor, the electrons move through the metal layer creating a current that can be measured.

Phototubes or photoemissive cells: An evacuated glass bulb is used and inside it, a cathode is placed along with an anode. The photocathode is coated with a light-sensitive layer like potassium oxide or silver oxide. When radiation hits the cathode, electrons are emitted and flow to the anode which creates an observable current.

Photomultipliers: These detectors use a vacuum tube, a fixed emissive cathode, many dynodes, and an anode. When the radiation’s electrons hit the first dynode, more electrons are emitted which strike the second dynode, which then emits even more electrons. This continues until the electrons are gathered by the anode and the resulting current is looked at.

Detectors for NIRS are commonly based on silicon, lead-sulfate (PbS), and indium gallium arsenide (InGaAs) photoconductive material. For analysis of short NIR wavelengths anything under 1000 nm, silicon-based charge-coupled devices or CCD are used. Both InGaAs and PbS are widely used due to their high response speed however, they are not as sensitive as CCDs.

FiltersFilters for UV-Vis also known as monochromators, consist of an entrance slit, collimating lens, dispersing device, a focusing lens, and an exit slit. These filters can be characterized as either interference or absorption filters. In an interference filters, a dielectric layer is used and only specific in-phase wavelengths can be reflected and recorded. In absorption filter, specific colored plates are used to absorb certain wavelengths leaving only the spectra that is to be observed. Two common filters that are used in NIRS are interference filters and acousto-optic tunable filters (AOTF). Interference filters, also called Fabry-Pérot filters, are narrow bandpass filters that use mirrors and a resonance cavity to filter out unwanted wavelengths that pass through it. AOTFs also called Bragg cells, use soundwaves to shift or diffract unwanted frequencies of light. In chemical imaging, the NIR spectrum requires the use of a 2D array detector used with an acousto-optic tunable filter.

DispersionIn UV-Vis spectroscopy, the dispersive devices used are prisms and grating. NIRS uses primarily grating as a dispersion technique. Prisms are semi-transparent in nature and made from glass, quartz, fused silica, or other transparent material. Depending on the geometry and the substance used, prisms are able to bend the light that passes through them. If white light passed through a glass prism the resulting bent light would be a rainbow. Grating disperses light either by diffracting it or through transmission. Transmission grating uses a series of grooves at specific angles that are able to refract the incoming light. On the opposite side of the grating, the light is dispersed at a fixed angle. Diffraction grating is similar, except instead of refracting the incoming light it reflects it. The incoming polychromatic light bounces off of the grating and diffracts it into multiple monochromatic beams. One of these beams can then be then isolated by angling it through an exit slit.

NIRS InterferometerInterferometry superimposes electromagnetic waves to interfere with the incoming waves so that they may be analyzed. An alternative to light diffraction, interferometers use beam splitters and measure the intensities of individual NIR wavelengths. The polychromatic wave is split into two beams, both of which are analyzed for NIR wavelengths. The minor offset between the two beams readouts is called an interferogram. Fourier transform near-infrared spectrometer, a well known NIRS technique, utilizes an interferometer.

NIRS has many applications across a variety of fields, including the medical profession. Their applications are usually reserved for analyzing the oxygen saturation of hemoglobin within the microcirculation. When used to look specifically at the oxygenation levels going to the brain, the technique is referred to as cerebral NIRS. The brain is one of, if not the most important organs in your body, and being able to non-invasively examine it is extremely important. When there is internal bleeding in the skull blood tends to pool in the affected area. Cerebral NIRS would be able to detect this quickly and without invasive procedures. Additionally, as different parts of the brain become active the oxygen levels in those parts change. Cerebral NIRS would be a smaller, easier to use, and cheaper device than current solutions.

Near-infrared spectrometers can be extremely expensive, but that should not stop you from acquiring the equipment that you or your lab needs to succeed. We at Excedr offer a comprehensive leasing program that can help you finance this important piece of equipment while also giving you peace of mind with our worry-free preventive maintenance and repair coverage.

We Offer FT-NIR or UV-Vis Spectrometer Leases to Fit Every Need

Operating Lease

This off-balance sheet financing structure provides three options at the end of the term. The lessee has the option to return the equipment to the lessor, renew at a discounted rate, or purchase the instrument for the fair market value. Monthly payments are also 100% tax deductible which yields additional monetary savings.

Sale Leaseback

If you recently bought equipment, Excedr can offer you cash for your device and convert your purchase into a long-term rental. This is called a sale leaseback. If you’ve paid for equipment within the last ninety days, we can help you recoup your investment and allow you to make low monthly payments. This also frees up money in your budget rather than tying it down to a fixed asset.

Effect on Credit & Operating Capital

Leasing/renting does not hinder your future borrowing ability and allows you to keep your business credit line open for expansions, staffing, and other operational expenses. Additionally, it strengthens the cash flow of your business and keeps cash reserves free for business development opportunities.

Used Equipment

Unlike traditional financing and leasing companies, the Excedr program can accommodate refurbished/reconditioned equipment in addition to demo units. If you are looking for additional cost-savings, we recommend considering this option.

Speed of Approval

Excedr’s program allows you to respond quickly as your need for equipment and technology arises. You can be approved with minimal documentation and have the equipment you need in operation and generating revenue for your business quickly.